Abravise-containing contact lens cleaning materials

ABSTRACT

New cleaning solutions for contact lens have a surface active agent, an inorganic abrasive, and a suspending agent to provide a suspension in an aqueous solution or organic liquid.

This application is a continuation of application Ser. No. 702,367,filed Feb. 15, 1985, now abandoned which is a continuation ofapplication Ser. No. 455,972, filed Jan. 6, 1983, now U.S. Pat. No.4,534,878, issued Aug. 13, 1985, which is a continuation of applicationSer. No. 197,223, filed Oct. 15, 1980, now U.S. Pat. No. 4,394,179issued July 9, 1983, which is a continuation-in-part of application Ser.No. 051,960 filed June 25, 1979, now abandoned.

BACKGROUND OF THE INVENTION

It has long been recognized in the art that contact lenses must remainfree of surface deposits in order to maintain their wearing comfort andoptimum vision and reduce the potential for ocular change.Unfortunately, contact lenses are susceptible to acquiring surfacedeposits from exogenous sources (mascara, hair spray, etc.) andendogenous sources (mucous, oily meibomian secretions, etc.). Siliconecontaining contact lenses are the most vulnerable of all contact lensesto the acquisition of tenacious, waxy surface deposits that aredifficult, if not impossible, to totally remove without damaging thelens.

Previous hard and soft contact lens cleaning solutions have used avariety of water soluble cleansing agents, in addition to water solublehydrating polymers in sterile homogeneous aqueous solution. Othercleaning agents have employed thixotropic synthetic water solublepolymers and thixotropic synthetic clays with detergents to give stiffgels for the cleaning of hard contact lenses. The cleaning processinvolves removal of contaminants from the surfaces of the contact lenswithout scratching or otherwise affecting the lens material.

Abrasives are employed in the manufacturing of contact lenses in apolishing process which provides the contact lens with optical qualitysurfaces. Polishes are also employed to blend the edge of the lens andto make minor alterations in the power of the lens. Abrasive materialshave not been used in contact lens cleaning solutions heretofore,perhaps because such abrasives would have the propensity to scratch orotherwise alter the surface of the plastic contact lens, thus leading toa reduction in optical clarity as well as enhanced eye irritation.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a contact lens cleaningmaterial which consists essentially of a surface active agent, aninorganic abrasive and a suspending vehicle which material is highlyuseful as a cleaner enabling superior cleaning of silicone-containingplastic contact lenses while also useful as a cleaner and/orcleaner/polisher for other contact lens materials.

It is still another object of this invention to provide a method ofcleaning of ophthalmic contact lens which method comprises applying acleaning solution containing an abrasive to a surface of the lens andmildly abrading said surface to remove unwanted surface deposits ifpresent without changing the power of the contact lens.

According to the invention, a contact lens cleaning material consistsessentially of a surface active agent, an inorganic abrasive and asuspending vehicle such as water or an organic liquid. Means areprovided to maintain the surface active agent and abrasive insubstantially uniform suspension so that the solution is capable ofcleaning a contact lens without adversely affecting the lens. Thematerial is preferably a liquid solution but can be in a paste or gelform. The cleaner can have a polishing action as where the properabrasive material is chosen and its concentration increased. Preferablythe abrasive is of a proper particle size distribution so as not toscratch the lens when used.

According to the method of this invention, an opthalmic contact lens iscleaned by mildly abrading the surface of the lens in the presence of acleaning solution containing an abrasive, a surface active agent, aliquid vehicle and a suspending agent. The cleaning solution is appliedand the surface of the lens mildly abraded to remove unwanted surfacedeposits, if present, without imparting scratches in the lens surfacesand without changing the curvature or power of the lens surfaces. Byincreasing the abrasive content in the formulation a cleaner/polish canresult. When used properly, the cleaner/polish will not only clean thesurface of the lens but also provide a polishing action which removesany scratches present, thus restoring the optical integrity of the lenssurface. Additionally, the cleaner/polish can be used to make minoradjustments in the power of a contact lens.

It is a feature of this invention that there is multifold enhancement ofthe cleaning effectiveness of certain surface active agents byincreasing the friction produced as the surface active agent is rubbedover the plastic surfaces. This is accomplished by the introduction intothe surface active agent solution of solid abrasive particles the sizeand concentration of which can be varied according to the functiondesired for the formulation. The particle size normally utilized iscomparable to, or smaller than, the abrasive used to polish lenssurfaces during manufacture as is conventionally known. The particlesremain uniformly suspended in the surface active agent solution withoutsettling since settling could vary the effectiveness of the cleaner andwithout aggregating which could cause scratches on the lens surface.

It is another feature of this invention that the suspending agent forthe abrasive particles is such that the overall suspension is stablesubstantially indefinitely. The cleaning solution may containsterilizing and buffering agents as well as a fragrance. In certaincases it may be possible to utilize a surfactant for both suspending theabrasive particles and providing cleaning action. However, it is morecommon to use a high concentration of a water soluble salt or an organicpolymer to act as a suspending agent.

Although the cleaning solutions described in this application areespecially useful for cleaning and/or cleaning and polishing hard, gaspermeable contact lesnes containing siloxane, they are also useful forhard contact lenses fabricated from polymethyl methacrylate, siliconesand cellulose acetate butyrate as well as other plastics and othermaterials used for ophthalmic contact lenses.

DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred formulation of the novel contact lens cleaning solution ofthis invention utilizes a surface active agent with an abrasive forcombined chemical and mechanical cleaning action and a suspending agentfor the abrasive such that a stable suspension is formed, in an aqueoussolution.

The preferred surface active agents are detergents o surfactants such asanionic sulfates conforming to the following general structure:

    C.sub.n H.sub.n+1 O(CH.sub.2 CH.sub.2 O).sub.x SO.sub.3.sup.- R.sup.+

where

x varies from 0 to 10

n varies from 8 to 20

R⁺ is Na⁺, K⁺, NH⁺ ₄ 1/2Mg⁺⁺, HN⁺ (CH₂ CH₂ OH)₃

Examples of such detergents include:

Sodium lauryl sulfate

sodium cetyl sulfate

sodium octyl sulfate

sodium tridecyl sulfate

sodium oleyl sulfate

sodium tridecyl ether sulfate

triethanolamine lauryl sulfate

ammonium lauryl ether sulfate

sodium lauryl ether sulfate

magnesium lauryl sulfate

The abrasive compound or compounds are water insoluble inorganiccompounds employed for their abrasive characteristics. The abrasivematerial is a relatively hard, tough substance composed of irregularlyshaped particles and is oridinarily used for grinding, smoothing, andpolishing. In general, the abrasive industry teaches that fine grindingabrasives have average particle size ranging between 10 and 100 micronswhile polishing abrasives have average particle sizes below 10 microns.Other parameters that determine the utility of effectiveness of anabrasive would include particle size distribution, particle shape,particle density, and particle hardness. While it is generallypreferable to employ abrasives with an average particle size of 10microns or less in this invention, it has been found of up to 20 micronsor less are suitable.

Such abrasives could be chosen from:

Aluminas--calcined, hydrated, tabular

Silicas--amorphous, crystalline or synthetic such as silica gels

Aluminum silicates (Kaolin)

Magnesium silicates (Talc)

Magnesium carbonate

Magnesium oxide

Calcium carbonate

Titanium dioxide

Zirconium oxide

Cerium oxide

Cesium oxide

Barium sulfate (Barytes)

Beritonite

Pumice

The suspending agent or agents in this composition must provide a stablesuspension of the abrasive in the cleaning solution. Such suspensionscould be achieved by increasing the viscosity of the aqueous solutionthrough the addition of soluble salts and/or hydrophilic polymers or bythe addition of water soluble neutral or ionic polymers which caninteract with the surface of one or more inorganic abrasive particles,thus preventing or hindering precipitation from occurring.

Such suspending agents can be one or more of the following:

alkali metal halides (high concentration)

alkaline earth metal salts (moderate concentration)

polyvinyl alcohol

polyacrylamide

hydrolyzed polyacrylamide

polyacrylic acid

xanthan gum

hydroxyethyl cellulose

hydrolyzed polyacrylonitrile starch

carboxymethyl cellulose

cellulose sulfate

methyl cellulose

methyl hydroxyethyl cellulose

methyl hydroxypropyl cellulose

poly-N-vinylpyrrolidone

guar gum

carboxymethyl guar gum

hydroxyethyl guar gum, hydroxypropyl guar gum

hydrolyzed polyacrylonitrile 2-acrylamido-2-methylpropane sulfonatestarch

clays such as bentonite, montorillonite and hectorite

neutral, cationic and anionic detergents

partially acetylated cellulose

gelatin

polyethylene glycol and oxide, polyethylene oxide/polypropylene oxideblock copolymers

K-carageenan

Buffering agents can be used and are preferably those commonly employedin the art within a pH range of 5 to 8, and usually between 7 and 8.Such buffers include boric acid, sodium borate, phosphoric acid,disodium phosphate and sodium bicarbonate.

The use of salts as suspending agents generally renders the cleaningsolution sterile; however, in cases where sterility must be imparted,anti-microbial compounds can be used. Such compounds includechlorhexidine and its salts, benzalkonium chloride, phenyl mercuricacetate, phenethyl alcohol, methyl or propyl paraben, cetyl pyridiniumchloride, thimerosal and the like, in possible conjunction with EDTA.

Fragrances such as wintergreen or peppermint can be used if desired.

In the simplest fashion, the contact lens is cleaned by immersing thelens in the cleaning solution or spraying the lens and by providingagitation of the solution such as by rubbing, shaking, or wiping of thecleaning solution on the lens surface. The lens is then rinsed withwater and inserted directly into the eye or it is placed in a soakingand/or wetting solution prior to insertion.

Specific examples of this invention are given below but are not meant inany way to limit this invention.

EXAMPLE I

Formulation:

Sodium tridecyl ether sulfate (30%): 80 gms

distilled water: 160 gms

sodium chloride: 20 gms

silica (Syloid 63-- a trademarked 24 gms product of W.R. Grace Co. ofBaltimore, Maryland, containing silica gel of about 9 micron averageparticle size): 24 gms

The sodium chloride was dissolved in the water followed by the additionof the silica powder. Once the silica had been dispersed thoroughly thesurfactant was added and mixing continued until a smooth viscoussuspension was achieved. No settling of the abrasive was noted aftereight months of shelf storage.

EXAMPLE II

Formulation:

Sodium tridecyl ether sulfate (30%): 133 gms

distilled water: 267 gms

sodium chloride: 30 gms

silica (Syloid 53): 8 gms

Preparation was identical to that described in Example I.

EXAMPLE III

Formulation:

Sodium tridecyl ether sulfate (30%): 133 gms

distilled water: 267 gms

sodium chloride: 30 gm

silica (Syloid 63): 1 gm

Preparation was identical to that described in Example I.

EXAMPLE IV

    ______________________________________                                        Formulation:     A        B         C                                         ______________________________________                                        sodium tridecyl ether sulfate                                                                  133 gms  133 gms   133 gms                                   (30%)                                                                         distilled water  267      267       267                                       sodium chloride   30       30       --                                        silica (Syloid 63)                                                                              12      --        --                                        ______________________________________                                    

Cleaning solutions were prepared in the same manner as that described inExample I.

Contact lenses having a high silicone content characteristically developa tenacious waxy surface deposit that is difficult and often impossibleto remove with solvents, surfactants or polishing without damaging thesurfaces of the lenses. Such deposits are best visualized by studying arinsed and dried lens against a black background (with aself-illuminating binocular microscope and can be quantitated by grading1 to 4 according to surface area and thickness (opaqueness), a rating of4 indicating a severe deposit. Sixty pairs of lenses having roughlysymmetrical surface deposits of grade 2 or greater were subjected to thefollowing procedure: one lens of each pair was cleaned manually usingformulation "A". The companion lenses were broken up into three groupsof twenty. One group was cleaned manually with formulation "B", thesecond group with formulation "C" and the final group with variouscommercial contact lens cleaners (solutions and gels). It was found thatformulation "B" and "C" were equally effective but that formulation "A"was manifold more effective than formulation "B" or "C" in all cases. Infact, formulation "B" and "C" were relatively ineffective in removinggrade 4 deposits whereas this invention (formulation "A") was veryeffective in all cases. Finally, none of the commercial contact lenscleaners was more effective than formulations "B" and "C" and many wereless effective. This example points out the utility of a suspendedabrasive in providing improved cleaning action over simple surfactantsolutions.

EXAMPLE V

The cleaning solution described in Example III was provided to a numberof patients at the commencement of their wearing newly fabricated hardcontact lenses (containing silicone). They were instructed to cleantheir lenses nightly with this formulation. Their lenses were inspectedafter 6 months and compared with the lenses of a similar group ofsubjects who cleaned their lenses nightly with a variety of commercialcontact lens cleaners. The lenses of patients using the cleaningsolution of Example III were significantly freer of surface deposits andwere, as a rule, more comfortable.

The cleaning solution described in Example III was also given to a smallgroup of conventional polymethyl methacrylate contact lens wearers whocomplained of blurred vision as the result of the development of "dry"spots on the front surface of their lenses that recurred when cleanednightly by a variety of commercial contact lens cleaners, solvents, orpolishing. In all cases, the nightly use of this invention eliminatedthe hydrophobic or dry areas and the subjects' vision remained clearduring their daily wearing schedule.

EXAMPLE VI

The surfaces of all hard contact lenses eventually become scratched.Conventional polishes remove shallow scratches and smooth the ridgesadjacent to deeper scratches, thereby improving the comfort and opticsof the lenses. However, many of these scratched contact lenses also havesignificant surface deposits which are not removed by polishing. Infact, polishing contact lens surfaces that have heavy deposits maysimply spread and redistribute the deposits thereby reducing the surfacewettability even further. The cleaning solution described in Example Icombines the function of a cleaner (to remove surface film) and a polish(to remove surface scratches) and it is far more effective than using acleaner and a polish in separate operations. A cleaner/polish such asdescribed in Example I is then particularly useful to the practitionerfor restoring the optics and wettability of hard contact lenses.

EXAMPLE VII

Formulation:

Sodium tridecyl ether sulfate (30%): 100 gms

4% HEC solution: 200 gms

aluminum oxide (0.06 micron): 10 gms

Dissolve 4% by weight hydroxyethyl cellulose (cellosize QP-40, a productof Union Carbide Corp. of New York, NY) in distilled water. Thesurfactant is then added and the solution mixed well. The aluminum oxideis then blended thoroughly into this solution until a smooth viscoussolution is achieved.

This Example demonstrates the use of a water soluble polymer to suspendthe abrasive powder.

EXAMPLE VIII

Formulation:

sodium tridecyl ether sulfate (30%): 100 gms

distilled water: 200 gms

Hydrite 10 (kaolin clay): 30 gms

sodium chloride: 25 gms

The preparation was identical to that described in Example I.

This Example demonstrates the use of kaolin, a material which imparts a"milder" abrasive action when compared to silica or alumina.

EXAMPLE IX

Formulation:

sodium tridecyl ether sulfate (30%): 100 gms

glycerin: 200 gms

silica (Syloid 63): 3 gms

The surfactant was dissolved in glycerin then the silica was blendedinto this solution.

This Example demonstrates the use of an organic liquid in conjunctionwith the surfactant to achieve a transparent cleaning solution.

EXAMPLE X

The following cleaner composition was used as the base formulation forclassifying various abrasives with respect to their tendency to scratchcontact lenses and contact lens material..

Sodium tridecyl ether sulfate (30%): 100 gms.

distilled water: 80 gms.

sodium chloride: 15 gms.

abrasive: 30 gms.

The sodium chloride was dissolved in the water followed by the additionof the abrasive powder. Once the powder had been dispersed thoroughlythe surfactant was added and mixing continued until a smooth viscoussuspension was achieved.

EXAMPLE XI

A "Manual Cleaner Analysis" was performed to estimate the potential of acleaner formulation to scratch contact lenses under actual useconditions. The level of abrasive in the cleaner formulation wasdeliberately set at a high level in order to more easily differentiatebetween the various abrasives tested.

Samples for this analysis were "The Boston Lens"™ contact lenses. Theseare highly oxygen permeable, siloxane based hard contact lensesoriginating from Polymer Technology Corp. of Wilmington, Massachusetts.The surfaces were highly polished and of excellent optical quality.

The tests were performed by placing a small amount, 5 drops, of thecleaner formulation into the palm of the hand. A test lens was placed onthe print area of the index finger of the other hand. The convex surfaceof the lens was then pressed into the cleaner, against the palm, andmoved in a circular motion making 50 circuits of the palm area. The lenswas rinsed with water, dried, and inspected for scratches undermagnification (20x).

EXAMPLE XII

A "Cleaning Action Simulation" test was devised to classify variousabrasives, contained in a cleaner formulation, as to their propensity toscratch the surface of a lens material. The test was designed toaccurately and reproducibly determine the effects of long term patientuse of a cleaner compound, containing an abrasive material, on theircontact lenses. The level of abrasive in the cleaner formulation waspurposely set at a high level so that long term effects could beestimated in a relatively short testing period.

The lens material utilized throughout the testing program was "TheBoston Lens"™ material, a siloxane based composition with a RockwellHardness of approximately 80 on the M scale. Samples were in the form of3/16"×1/2" discs (buttons) with the testing surface polished torepresent the high quality optical finish found on actual contactlenses.

A modified crockmeter was utilized as the testing apparatus with the armexerting a total load of 150 gms on the sample button. After mounting abutton, the arm was moved to its farthest left extension point andsupported off the base. A piece of velveteen cloth was stretched acrossthe base of the simulator and secured. The cleaning composition to betested was applied to the cloth from an applicator bottle along thestroke path (approximately 1" wide×5" long) the lever arm was loweredonto the cloth and the simulator activated. The action of the simulatorwas such that the button was rubbed back and forth on the cleaner for apredetermined number of strokes (set on the counter) over a pathtotaling 4" in length. The sample button was removed, rinsed with water,dried, and inspected for scratches under magnification (20x).

The following scale was used to qualitatively rank abrasives accordingto their ability to scratch the surface of the sample.

0-- no scratching

+--slight scratching

++--moderate scratching

+++--heavy scratching

The above ranking reflects scratch density.

EXAMPLE XIII

This Example illustrates the use of IMSIL Silicas (a synthetic silicasold by Illinois Minerals Co. of Illinois) as the abrasive component ina contact lens cleaning composition. The cleaner formulation is given inExample X and the testing protocol in Examples XI and XII.

The IMSIL grades of micronized silica, when evaluated by the Manualcleaning procedure, produced only slight scratching in the worst case(IMSIL A-25). When evaluated in the Cleaning Action Simulator all fourgrades of IMSIL imparted a moderate degree of scratching. Thesematerials are potentially useful in the cleaner compositions disclosedin this invention, particularly those IMSIL grades that have an overallparticle size distribution substantially below 10 to 15 microns (IMSILA-15, A-10, and A-108).

    ______________________________________                                        Supplier:     Illinois Minerals Co.                                           Material:     Micronized Amorphous Silica                                     Composition:  Silicon Dioxide (SiO.sub.2)                                     Specific Gravity:                                                                           2.65                                                                             IMSIL   IMSIL   IMSIL IMSIL                                                   A-25    A-15    A-10  A-108                                  ______________________________________                                        Mean Particle Size (Microns)                                                                   4.3     2.9     2.2   1.8                                    Particle Size Distribution                                                    40 Micron Diameter, Below                                                                      99.0%   100.0%  100.0%                                                                              100.0%                                 20 Micron Diameter, Below                                                                      96.0%   100.0%  100.0%                                                                              100.0%                                 15 Micron Diameter, Below                                                                      90.0%   99.0%   100.0%                                                                              100.0%                                 10 Micron Diameter, Below                                                                      77.0%   96.0%   99.0% 100.0%                                 5.0 Micron Diameter, Below                                                                     51.0%   70.0%   76.0% 96.0%                                  ______________________________________                                        MANUAL CLEANING ANALYSIS                                                      ABRASIVE          COMMENTS                                                    ______________________________________                                        IMSIL A-108       Polishing Type Action                                       IMSIL A-10        Very slight scratching                                      IMSIL A-15        Very slight scratching                                      IMSIL A-25        Slight scratching                                           ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                   NUMBER OF STROKES                                                  ABRASIVE     10     25        100   250                                       ______________________________________                                        IMSIL A-108  ++     ++        ++                                              IMSIL A-10   ++     ++        ++                                              IMSIL A-15   ++     ++        ++                                              IMSIL A-25   +      ++        ++                                              ______________________________________                                    

EXAMPLE XIV

This Example illustrates use of a silica as the abrasive component in acontact lens cleaning composition. The cleaner formulation is given inExample X and the testing protocol in Examples XI and XII.

The use of silica with an average particle size of 14 microns and asubstantial number of particles above 30 and 40 microns demonstrates theeffect of an abrasive outside the scope of this invention. extremelyheavy scratching was inflicted on both contact lenses and buttonscleaned with a composition containing this abrasive.

    ______________________________________                                        Supplier:    Whittaker, Clark and Daniels, Inc.                               Material:    219 Silica                                                       Composition: Silicon Dioxide (SiO.sub.2)                                      Specific Gravity:                                                                          2.65                                                             Average Particle Size (Microns) 14                                            Typical Particle Size Distribution:                                           Microns  % Less Than   Microns  % Less Than                                   ______________________________________                                        40       96            5        20                                            30       85            2        9                                             20       65            1        7                                             10       40                                                                   ______________________________________                                        MANUAL CLEANING ANALYSIS                                                      Abrasive          Comments                                                    ______________________________________                                        Silica            Inflicts very heavy                                         219               scratching on lens                                          ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                  NUMBER OF STROKES                                                   Abrasive    10      25         100  250                                       ______________________________________                                        Silica 219  +++                                                               ______________________________________                                    

EXAMPLE XV

This example illustrates the use of lo micron Talc as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Lo micron Talc has a median particle size between 1 and 2 microns and noparticles over 15 microns. When evaluated in the cleaner formulationslight scratching of both contact lenses and buttons was noteddemonstrating the marginal suitability of this abrasive.

    ______________________________________                                        Supplier:    Whittaker, Clark and Daniels, Inc.                               Material:    2610 Lo Micron Talc                                              Composition: Silicon Dioxide/Magnesium Oxide                                               (SiO.sub.2 /MgO)                                                 Specific Gravity:                                                                          2.70                                                             Typical Particle Size Distribution                                            Microns  % Less Than   Microns  % Less Than                                   ______________________________________                                        15       100           3        76                                            10       98            2        64                                             5       90            1        40                                             4       84            0.5      22                                            ______________________________________                                        MANUAL CLEANING ANALYSIS                                                      Abrasive          Comments                                                    ______________________________________                                        Lo Micron Talc    Very slight scratching                                      ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                    NUMBER OF STROKES                                                 Abrasive      10     25        100  250                                       ______________________________________                                        Lo Micron Talc                                                                              0      ++                                                       ______________________________________                                    

EXAMPLE XVI

This example illustrates the use of Vibroxide-M2 as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Vibroxide-M2, a zirconium oxide based abrasive, sold by TranselcoDivision of Ferro Corp. appears to be unsuitable in a contact lenscleaning formulation. This example demonstrates that a particle sizerange below 10 microns does not necessarily ensure the usefulness of anabrasive in this invention.

Supplier: Ferro Corp.--Transelco Division

Material: Vibroxide--M2

Composition: 56% Zirconium Oxide (ZrO₂)

Average Particle Size (Microns): 1.2-1.8

Particle Size Distribution (Microns): 0.5-5

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive      Comments                                                        ______________________________________                                        Vibroxide-M2  Slight scratching                                               ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                  NUMBER OF STROKES                                                   Abrasive    10      25         100  250                                       ______________________________________                                        Vibroxide-M2                                                                              +       ++         ++                                             ______________________________________                                    

EXAMPLE XVII

This example illustrates the use of a silica as the abrasive componentin a contact lens cleaning composition. The cleaner formulation is givenin Example X and the testing protocol in Examples XI and XII.

Illinois Minerals Co. grade 1160 silica contains many particles over 37microns (400 mesh Tyler screen) and produced moderate scratching inaccordance with the testing procedures taught in this disclosure. Thismaterial was judged unsuitable for use in a contact lens cleanerformulation.

Supplier: Illinois Minerals Co.

Material: Air Floated Amorphous Silica

Composition: Silicon Dioxide (SiO₂)

Specific Gravity: 2.65

    ______________________________________                                                          GRADE 1160                                                  ______________________________________                                        Mean Particle Size (Microns)                                                                      7.0                                                       Particle Size Distribution                                                    200 Mesh Tyler Screen (Thru)                                                                      99.98%                                                    325 Mesh Tyler Screen (Thru)                                                                      96.98%                                                    400 Mesh Tyler Screen (Thru)                                                                      92.65%                                                    ______________________________________                                    

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive          Comments                                                    ______________________________________                                        Grade 1160        Definite scratching                                         ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                  NUMBER OF STROKES                                                   Abrasive    10     25          100  250                                       ______________________________________                                        Grade 1160  ++     ++          ++                                             ______________________________________                                    

EXAMPLE XVIII

This example illustrates the use of Syloid synthetic silicas in acontact lens cleaning composition. The cleaner formulation is given inExample X and the testing protocol in Examples XI and XII. The Syloidseries of silica material are classified as "hydrogel" type silicaswhich refers to the method of manufacture. They are unique in that theparticles of Syloid are made up of small, well rounded, clusters and arequite porous. While the base silica itself has a specific gravity of 2.1the porosity included in a Syloid particle lowers the density to 1.05gm/cc or less and in fact, Syloid grades are differentiated by density.

regular density: 1.05 gm/cc

intermediate density: 0.65 gm/cc

low density: 0.55 gm/cc

The results of scratch testing clearly demonstrates the usefulness ofSyloid silicas in a contact lens cleaning formulation.

It is interesting to note the difference between Syloid 63 and Syloid76, both of equal particle size. The higher density Syloid 63demonstrates a slight tendency toward scratching contact lenses whilethe intermediate density Syloid 76 does not.

Also, because of the unique particle geometry larger size particles(Syloid 620) can be used successfully in the invention.

    ______________________________________                                        Supplier:  W. R. Grace Co. - Davison Chemical Division                                   Baltimore, Maryland                                                Material:  Synthetic Silica                                                   Composition:                                                                             Silicon Dioxide (SiO.sub.2)                                        Specific Gravity:                                                                        2.1                                                                         Average    Silica       Average                                               Particle Size                                                                            Particle Density                                                                           Pore Diameter                                Grade    (Microns)  (gms/cc)     (angstroms)                                  ______________________________________                                        SYLOID 86                                                                              2          0.55         200                                          SYLOID 72                                                                              4          0.65         150                                          SYLOID 74                                                                              8          0.65         150                                          SYLOID 76                                                                              9          0.65         150                                          SYLOID 620                                                                             20         0.65         150                                          SYLOID 63                                                                              9          1.05          25                                          ______________________________________                                    

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive          Comments                                                    ______________________________________                                        SYLOID 86         No scratching                                               SYLOID 72         No scratching                                               SYLOID 74         No scratching                                               SYLOID 76         No scratching                                               SYLOID 620        No scratching                                               SYLOID 63         Very slight scratching                                      ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                   NUMBER OF STROKES                                                  Abrasive     10     25         100  250                                       ______________________________________                                        SYLOID 86    0      0          +                                              SYLOID 72    0      0          0    0                                         SYLOID 74    0      0          +                                              SYLOID 76    0      0          0    0                                         SYLOID 620   0      0          +                                              SYLOID 63    ++     ++         ++                                             ______________________________________                                    

EXAMPLE XIX

This example illustrates the use of Colloidal Kaolin as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Both Kaolin abrasives evaluated had a median particle size of 1 micronbut contained a substantial fraction (10%) above 10 microns. However,very little, if any, scratching was noted on contact lenses and buttonscleaned with compositions containing Kaolin as the abrasive component.The results may reflect the relatively low hardness of this mineral anddemonstrate the usefulness of Kaolin in the cleaner compositionsdisclosed in this invention.

    ______________________________________                                        Median Particle Size (Microns)  1.0                                           Typical Particle Size Distribution:                                           Microns  % Less Than  Microns  % Less Than                                    ______________________________________                                        GRADE: 347 English Collidal Kaolin USP                                        40       99           2        81                                             10       90           1        50                                             4        94           0.5      25                                             3        90                                                                   GRADE: 2749 Colloidal Kaolin USP                                              10       90           1        50                                             4        94           0.5      30                                             3        90                                                                   2        80                                                                   ______________________________________                                         Supplier: Whittaker, Clark and Daniels, Inc.                                  Material: Colloidal Kaolin                                                    Composition: Silicon Dioxide/Aluminum Oxide (SiO.sub.2 /Al.sub.2 O.sub.3)     Specific Gravity: 2.60                                                   

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive           Comments                                                   ______________________________________                                        Kaolin 347         No scratching -                                                               possible polishing                                                            action                                                     Kaolin 2749        No scratching                                              ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                  NUMBER OF STROKES                                                   Abrasive    10     25         100   250                                       ______________________________________                                        Kaolin 347  +                                                                 Kaolin 2749 0      0          0     0                                         ______________________________________                                    

EXAMPLE XX

This example illustrates the use of Transelco Alumina as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Three grades of alumina, Alox 721, ALOX PG and Micronal 707, supplied byTranselco were judged to be satisfactory as the abrasive component inthe contact lens cleaning formulations disclosed in this invention. Morespecifically, the Alox 721 would be preferred based on the resultsobtained in the Cleaning Action Simulator.

    ______________________________________                                        GRADE                                                                                           ALOX    ALOX    MICRONAL                                                      721     PG      707                                         ______________________________________                                        Average Particle Size (Microns)                                                                 0.2     1.2-1.8 2-3                                         Particle Size Distribution                                                                      --      0.6-5   0.5-15                                      (Microns)                                                                     ______________________________________                                        MANUAL CLEANING ANALYSIS                                                      Abrasive             Comments                                                 ______________________________________                                        ALOX 721             No scratching                                            ALOX PG              No scratching                                            MICRONAL 707         No scratching                                            ______________________________________                                         Supplier: Ferro Corp. Transelco Division                                      Material: Alumina Polishing Compounds                                         Composition: Aluminum Oxide (Al.sub.2 O.sub.3)                           

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                    NUMBER OF STROKES                                                 Abrasive      10     25        100  250                                       ______________________________________                                        ALOX 721      0      0         0                                              ALOX PG       0      0         ++                                             MICRONAL 707  0      0         ++                                             ______________________________________                                    

EXAMPLE XXI

This example illustrates the use of Titanium Dioxide as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Both titanium dioxide abrasives cited in this example have narrowparticle size distributions with a maximum of 1 micron. Cleaningformulations containing either grade were judged satisfactory on thebasis of scratch testing.

Supplier: Whittaker, Clark and Daniels, Inc.

Material: Titanium Dioxide

Composition: Titanium Dioxide (TiO₂)

Specific Gravity: 3.90

GRADE: 328 Titanium Dioxide

Particle Size

Maximum, Microns: 1.0

Average, Microns: 0.3

Dispersible Type: Oil

GRADE: 3328 Titanium Dioxide

Particle Size

Maximum, Microns: 1.0

Average, Microns: 0.3

Dispersible Type: Water

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive           Comments                                                   ______________________________________                                        Titanium Dioxide 328                                                                             No scratching                                              Titanium Dioxide 3328                                                                            Very slight scratching                                     ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                     NUMBER OF STROKES                                                Abrasive       10     25        100  250                                      ______________________________________                                        Titanium Dioxide 328                                                                         0      +                                                       Titanium Dioxide 3328                                                                        0      +                                                       ______________________________________                                    

EXAMPLE XXII

This example illustrates the use of Hydrated Alumina as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

The Hydrated alumina abrasives evaluated ranged in median particle sizefrom about 1 micron to over 45 microns. All three grades provedunsuitable in the cleaner formulation because of moderate scratching ofboth contact lenses and buttons.

Supplier: Whittaker, Clark and Daniels, Inc.

Material: Hydrated Alumina

Composition: 65% Aluminum Oxide (Al₂ O₃)

Specific Gravity: 2.42

GRADE: 604 Hydrated Alumina (Hydral 710) Typical Particles SizeDistribution

    ______________________________________                                               Microns                                                                              % less than                                                     ______________________________________                                               2      100                                                                    1      85                                                                     0.5    28                                                              ______________________________________                                    

GRADE: 614 Hydrated Alumina (C-331)

Median Particle Size (microns): 6.5-9.5

GRADE: 639 Hydrated Alumina (C-31)

Typical Particle Size Distribution

Thru 100 mesh, %: 98-99

Thru 200 mesh, %: 90-95

Thru 325 mesh, %: 35-70

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive           Comments                                                   ______________________________________                                        Hyd. Alumina 604   Definite scratching                                        Hyd. Alumina 614   Definite scratching                                        Hyd. Alumina 639   Definite scratching                                        ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                    NUMBER OF STROKES                                                 Abrasive      10     25         100  250                                      ______________________________________                                        Hyd. Alumina 604                                                                            ++     ++                                                       Hyd. Alumina 614                                                                            ++     ++                                                       Hyd. Alumina 639                                                                            ++     ++                                                       ______________________________________                                    

EXAMPLE XXIII

This example illustrates the use of Lo Micron Magnesium Silicate as theabrasive component in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

This abrasive has a median particle size between 1 and 2 microns andcontains approximately 4%, by weight, of particles above 10 microns. Theslight scratching of both contact lenses and buttons demonstrates themarginal suitability of this abrasive in a lens cleaner composition.

Supplier: Whittaker, Clark and Daniels, Inc.

Material: 399 Lo Micron Magnesium Silicate S.F.

Composition: Silicon Dioxide/Magnesium Oxide (SiO₂ /MgO)

Specific Gravity: 2.70

Typical Particle Size Distribution:

    ______________________________________                                        Microns  % Less Than  Microns  % Less Than                                    ______________________________________                                        20       100          4        80                                             15       98           2        60                                             10       96           1        36                                              5       84           0.5      16                                             ______________________________________                                    

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive            Comments                                                  ______________________________________                                        Magnesium Silicate  Slight scratching                                         ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                      NUMBER OF STROKES                                               ______________________________________                                        Abrasive       10     25        100  250                                      Magnesium Silicate                                                                           0      0              ++                                       ______________________________________                                    

EXAMPLE XXIV

This example illustrates the use of Novacite 1250 as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Malvern Novacite 1250 is composed of dense, irregularly shaped particleswith sharp edges present. The particle size distribution includesapproximately 35% of particles over 10 microns. These physicalcharacteristics render this abrasive unsuitable for use in the cleanercomposition disclosed in this invention, as evidenced by the scratchtesting results.

Supplier: Malvern Minerals Co.

Material: Platey Particulate Silica

Composition: Silicon Dioxide (SiO₂)

Specific Gravity: 2.65

    ______________________________________                                                         NOVACITE 1250                                                ______________________________________                                        Average Particle Size                                                                          6.5                                                          (Microns)                                                                     ______________________________________                                        Particle Size Distribution (% finer than sieve opening)                       Micron       U.S. Sieve Series                                                Diameter     Number                                                           ______________________________________                                        74           200           100.00%                                            53           270          100.00                                              44           325          99.99                                               37           400          99.92                                               30           475          99.10                                               20           625          92.00                                               15           950          86.30                                               10           1250         65.40                                                5           2500         19.84                                                3           4500         11.64                                                1           12500         3.45                                               ______________________________________                                    

MANULA CLEANING ANALYSIS

    ______________________________________                                        Abrasive           Comments                                                   ______________________________________                                        Novacite 1250      Definite scratching                                        ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                    NUMBER OF STROKES                                                 ______________________________________                                        Abrasive      10     25        100  250                                       NOVACITE 1250 ++     ++        ++                                             ______________________________________                                    

EXAMPLE XXV

This example illustrates the use of Meller Alumina as the abrasivecomponent in a contact lens cleaning composition. The cleanerformulation is given in Example X and the testing protocol in ExamplesXI and XII.

Of the four particle size grades of Alumina supplied by Meller Co.,three were judged unsatisfactory as the abrasive component in thecleaner composition. The lowest particle size average, Meller 0.3alumina, proved marginal in performance.

Supplier: Adolf Meller Co.

Material: Alumina Polishing Powder

Composition: Aluminum Oxide (Al₂ O₃)

Specific Gravity: 3.98

GRADES: By Average Particle Size

0.3 Micron

1.0 Micron

3.0 Micron

8.0 Micron

MANUAL CLEANING ANALYSIS

    ______________________________________                                        Abrasive          Comments                                                    ______________________________________                                        MELLER 0.3        Slight scratching                                           MELLER 1.0        Slight scratching                                           MELLER 3.0        Definite scratching                                         MELLER 8.0        Definite Scratching                                         ______________________________________                                    

CLEANING ACTION SIMULATOR ANALYSIS

    ______________________________________                                                  NUMBER OF STROKES                                                   Abrasive    10     25         100   250                                       ______________________________________                                        MELLER 0.3  0      0          ++                                              MELLER 1.0   +     ++         ++                                              MELLER 3.0  ++     ++         ++                                              MELLER 8.0  ++     ++         ++                                              ______________________________________                                    

While specific Examples of this invention have been shown and described,many variations are possible. When the cleaning solutions of thisinvention are used only as cleaners, the surface active agentspreferably comprise from 0.1 to 30% by weight of the material, theabrasive particles from 0.1 to 5% by weight and the suspending vehiclefrom 99.8 to 65.0% by weight, with a suspending agent based on 100 partsof the above being from 5 to 25 parts when inorganic salts are used andfrom 1 to 10 parts when polymers are used. The same suspending agentsare used when the cleaning solution is used to act as a cleaner/polishbut here the surfactant amount may range from 0.1 to 30% by weight andthe abrasive amount is raised to from 5 to 25% by weight while the wateror other suspending vehicle is used to bring the material to 100%. Whena paste or gel, rather than a free flowing liquid is desired, theformulation can carry from 15 to 40% by weight of the surface activeagent, from 5 to 50% by weight of an abrasive and the balance water orother solvent which is water soluble. Of course, one or more surfaceactive agents, abrasives, or solvents can be used in a singlecomposition if desired.

The particle sizes of the abrasives can vary greatly and depend on thetype of abrasive used. Although many factors, such as particle shape anddensity, influence the useful particle size range of the abrasive inthis invention an inverse correlation with hardness can be demonstrated.As the hardness of the particle material increases, the average particlesize necessary to avoid scratching contact lenses decreases. Thefollowing Table illustrates this correlation:

    ______________________________________                                                          Effective Average                                                                           Upper Particle                                       Mohs       Particle Size Size Limit                                    Material                                                                             Hardness*  (Microns)     (Microns)                                     ______________________________________                                        Alumina                                                                              9          0.01-0.5      <<10                                          Zirconia                                                                             7-8        0.05-1.0       <10                                          Silica 6-7        1-5           10-15                                         Kaolinite                                                                            2-3        1-10          20-30                                         Talc   1          1-10          20-30                                         Syloid 6-7        1-20          20-30                                         ______________________________________                                         *scale from 1 (Talc) to 10 (Diamond)                                     

In the actual practice of this invention the particle size distributionof the abrasive component may be altered by screening, ball milling orfiltration to remove or reduce the size of the larger particles present.In this manner, the particle size distribution can be tailored to theproper median particle size with no particles large enough to producescratching of hard contact lenses. Generally, particle sizes standardlyused for lens polishing in the ophthalmic industry can be used.

In general, the abrasives useful in this invention have an averageparticle size below 10 microns with few particles above 20 microns. TheSyloid series (or equivalent synthetic silicas such as Silcron, asynthetic silica solid by Pittsburg Plate Glass of Pittsburgh, Pa.) is anotable exception where average particle sizes of up to 20 microns canbe used successfully in the cleaner compositions disclosed in thisinvention. Such synthetic silicas have a well-rounded shape and arelight, spongy particles with high surface area. The synthetic silicasare referred to as silica gels and are often made by reaction betweensodium silicate and a mineral acid.

While specific Examples of the invention have been shown and described,many variations are possible. When the cleaning solutions of thisinvention are used only as cleaners, the surface active agentspreferably comprise from 0.1 to 30% by weight of the material, theabrasive particles from 0.1 to 5% by weight and the carrier vehicle suchas water from 99.8 to 69.9% by weight with a suspending agent based on100 parts of the above being from 5 to 25 parts when inorganic salts areused and from 1 to 10 parts when polymers are used. The same suspendingagents are used when the cleaning solution is used to act as acleaner-polisher but here the surfactant amount may range from 1 to 30%by weight and the abrasive amount is raised to from 5 to 25% by weightwhile the water or other suspending vehicle is used to bring thematerial to 100%. Whne a paste rather than a free flowing liquid isdesired, the formulation can carry from 15 to 40% by weight of thesurface active agent, from 20 to 50% by weight of an abrasive and thebalance water or other solvent which is water soluble. Of course, one ormore surface active agents, abrasives or solvents can be used in asingle composition if desired.

The particle sizes of the abrasives can vary greatly but they arepreferably that standardly used for lens polishing in the ophthalmicindustry. Particle sizes of silica for example, with an average of 9microns and a range of from 1 to 20 microns with an upper limit of 30microns in the form of Syloid 63, a trademarked product of DivisionChemcal, W. R. Grace, Co. of Baltimore, Md., can be used. Other sizeranges are possible.

In all cases, the surface active agent in the form of a detergent orsurfactant acts along with the abrasive to combine the best qualities ofboth which can result in synergistic action to clean contact lenses inaccordance with the method of this invention.

While surface active agents have been specifically noted in thisapplication, other surface active agents can be used. Such agentsassociate in water to form a colloidal particle known as a micelle. Thestructure is such that the hydrophobic hydrocarbon chains are inside,remote from the solvent and the polar head groups are on the surface ofthe particle. The presence of micelles in an aqueous solution endows itwith minute regions which are predominantly hydrophobic in nature. Thisallows for high solubility in water and good wetting of the materials.

What is claimed is:
 1. A hard contact lens cleaning material forcleaning plastic contact lenses and consisting essentially of a solutionof a surface active agent with said agent being present in an amount offrom about 0.1 to about 30% by weight,an inorganic silica gel abrasivehaving an average particle size of no more than 20 microns of a particlesize sufficient for use in lens polishing and in an amount of from 0.1to under 25% by weight, water as a suspending vehicle, and separatemeans to maintain said surface active agent and abrasive insubstantially uniform suspension so that said suspension is capable ofcleaning a contact lens without adversely affecting or scratching saidlens, said separate means being selected from the class consisting ofalkali metal halides, alkaline earth metal salts and hydrophilicpolymers, said surface active agent having the formula:

    C.sub.n H.sub.n+1 O(CH.sub.2 CH.sub.2 O).sub.x SO.sub.3.sup.- R.sup.+

wherex varies from 0 to 10 n varies from 8 to 20 R' is NA+, K+, NH₄ ',HN+, HN+(CH₂ CH₂ OH)₃.
 2. A hard contact lens cleaning material inaccordance with claim 1 wherein said separate means is sodium chloride.3. A hard contact lens cleaning material in accordance with claim 2wherein said abrasive is in an amount of from about 5% to about 25% byweight.